Used to is a semi-modal in English. We use it to talk about something we did in the past but don’t do anymore now.
Form of ‘used to’
➡️Positive: He used to drink a coke every day.
➡️Negative: He didn’t use to drink a coke every day.
➡️Question: Did he use to drink a coke every day?
Meaning of ‘used to’
In the example above, if we say “He used to drink a coke every day”, it means he had a habit of drinking a coke every day in the past, but he no longer does so nowadays .
If we say “He didn’t use to drink a coke every day”, it means he didn’t have a habit of drinking a coke every day in the past, but he does so nowadays. We can use either ‘did not use to’ or “used not to” to form the negative.
If we want to ask a question about habit in the past, we then say “Did he use to…”. In the above example, we have no idea if he had the habit of drinking a coke in the past. We then ask the question “Did he use to drink a coke every day”.
Pronunciation of ‘used to’
When we say ‘used to’, the preposition ‘to’ is a schwa which is not stressed. Meanwhile, the /d/ sound at the end of ‘used’ is deleted.